Generally, an optical device may be coupled to one side of a firearm so as to accurately aim an external target. In a particular case of a rifle among the firearms, aiming is achieved by aligning a line of sight between a front sight and a rear sight, in which speed showing how quickly the aiming is achieved to fire an aimed shot and accuracy showing how accurately the aimed shot hits the target are very important.
However, even a small shock or shake makes it difficult to align the line of sight, and it is disadvantageous for quick aiming requested at a short distance or in an urgent situation.
That is, an aimed-shooting method requires complicated procedures and time to acquire and ascertain a target, align the line of sight, aim at the target, etc. Also, because the front sight and the rear sight themselves are very small, not only they are susceptible to even a small shake, but also eyes are turned upon the front sight and the rear sight rather than the target or a frontward situation and therefore a field of view becomes narrow if excessive attention is paid to the alignment for the line of sight in order to accurately align the front sight and the rear sight.
Accordingly, an optical scope has been proposed to solve the above cumbersome alignment for the line of sight and improve the accuracy a little more.
The optical scope employs a magnifying-power optical system, which includes an objective lens and an objective lens reticle (i.e., the light of sight), to magnify a target, and is thus excellent in discerning the target, thereby enabling steady aiming through the reticle placed inside the scope.
Such an optical scope is broadly classified into a prism type and a relay lens type. FIG. 1 shows a structure of a prism type optical scope, and FIG. 2 shows a relay lens type optical scope.
First, referring to (a) of FIG. 1, the prism type optical scope includes an objective lens, a prism optical system, a reticle, an eyepiece lens, etc. FIG. 1 illustrates one sheet of the objective lens 12 and one sheet of the eyepiece lens 11, but many sheets of them are generally provided in practice to remove aberration or the like
If an image of an external object from the objective lens is formed at a position of the reticle, both the image and the reticle are magnified and viewed through the eyepiece lens, which is the principle of a telescope or scope. At this time, if the image from the objective lens is directly formed at the position of the reticle, the image is viewed as it is inverted. Thus, a prism is provided between the objective lens and the reticle to erect the image viewed through the eyepiece lens by inverting the inverted image again.
Referring to FIG. 2, the relay lens type optical scope includes an objective lens, a field lens, a reticle, a relay lens, an eyepiece lens, etc. FIG. 2 illustrates one sheet of the objective lens, one sheet of the field lens and one sheet of the eyepiece lens, but many sheets of them are generally provided in practice to remove aberration or the like.
If an image of an external object from the objective lens is formed at a position of the reticle, both the image and the mark of the reticle are formed again in front of the eyepiece lens and magnified and viewed through the eyepiece lens, which is the principle of a relay lens type telescope. At this time, if the image from the objective lens is directly formed on the reticle, the image is generally viewed as it is inverted. This inverted image is formed once gain by the relay lens and thus inverted again, so that the image in front of the eyepiece lens can be erect. Then, this erect image is magnified and viewed through the eyepiece lens.
Here, the field lens placed before and after the relay lens serves to condense a pencil of light entering the relay lens.
However, the above optical scopes are also susceptible to even a small shake like the front sight and the rear sight, and it is therefore to impossible to quickly achieve the aiming.
To solve such a problem, there has been proposed an optical dot-sight device in which no magnification is applied to an optical sight and a simple dot of sight is used instead of a complicate line of sight.
The optical dot-sight device is characterized in that it is simple and quick aiming is possible. Also, it is disadvantageous for quick aiming requested at a short distance or in an urgent situation.
In other words, it takes little time to align the line of sight, the aiming itself is achieved by quickly moving a light point to a target, and the field of view is very effectively secured. Therefore, the optical dot-sight device is of merit to reduce not only the time taken in the aiming but also an obstacle based on the aiming to the field of view and a situation judgment.
FIG. 3 is a schematic view of an optical dot-sight device. Referring to FIG. 3, the optical dot-sight device 100 includes an adjuster 120 placed on a top of a cylindrical sighting housing 110 and aligning an internal tube body, a fastening grill 130 detachably coupled to a rifle rear sight module (not shown) placed under the housing 110 through a rail way, a protective window 140 placed inside the housing 110, a light emitting diode (LED) 150 placed at a predetermined position of an inner side of the tube body within the housing 110 and emitting light, and a reflective mirror 160 having a certain curvature and placed behind the protective window 140 within the housing 110.
Here, the reflective mirror 160 is coated to make an observer's (i.e., user's) eyes see through toward a front end of the optical dot-sight device 100 and reflect a beam dot of the LED 150 having a wavelength of about 650 nm. Thus, the reflective mirror 160 makes the observer's (i.e., user's) eyes see through toward the front end of the optical dot-sight device 100 and reflects the beam dot of the LED 150 having a wavelength of about 650 nm.
An observer (i.e., user) fires when the LED light point and a target are aligned, thereby facilitating the aiming. In more detail, it is intended that the beam dot generated by the LED 150 placed inside the optical dot-sight device 100 is reflected by the reflective mirror 160 and parallel enters the observer's eyes, and this parallel is aligned with a bullet shooting axis of a barrel.
If the parallel of the optical dot-sight device 100 is not aligned with the bullet shooting axis of the barrel, the target is missed even though the observer aligns the beam dot of the LED 150 with the target. Accordingly, to align the parallel of the optical dot-sight device 100 with the bullet shooting axis of the barrel, the adjuster 120 having vertical and horizontal functions for aligning an inner tube body is provided to align an optical axis of the inner tube body with the bullet shooting axis of the barrel.
However, the optical dot-sight device has no function of magnifying an external target like a scope device, and thus needs to additionally have the optical scope.
Also, as the scope device is separately provided, an external target has to be first acquired through the scope device and then aimed again through the optical dot-sight device.